Paperboard cartons for storing granular materials, such as laundry detergents, are known in the art. These cartons can comprise a closed bottom container having an opening through which the granular materials can be viewed and removed. A recloseable lid covers the opening to seal the container from the environment. Often times, the users perception of the efficacy of the granular material stored in the carton is based upon the visual appearance of the granular material. For example, users of granular laundry detergents often gauge the detergents effectiveness by the color of the detergent, wherein the more white the color, the more effective the detergent is perceived to be. While dyes and optical brighteners can be used to adjust the color of a laundry detergent, various types of lighting can still affect the visual appearance of the laundry granules. Still further, there can be differences between geographic regions regarding which color, or even shade of a color, is perceived to represent an effective laundry detergent.
As such, there exists a need for simplified structures and methods for adjusting the visual appearance of granular materials without changing the composition or recipe of the granular material in order to provide more visually pleasing granular materials. Still further, there exists a need to provide simplified structures and methods for adjusting the visual appearance of a granular material by changing any one of a number of radiant characteristics of the granular material. Yet further, there exists a need to provide structures and methods which can shift the radiant characteristics of more than one granular material stored in the container.